Ratchet potential for fluxons in Josephson-junction arrays

Abstract

(received; accepted) PACS. 74.50+r – Proximity effects, weak links, tunneling phenomena and Josephson effects. PACS. 05.40+j – Fluctuation phenomena, random processes and Brownian motion.. PACS. 85.25+Na – Superconducting microelectronic circuits.. Abstract. – We propose a simple configuration of a one-dimensional parallel array of Josephsonjunctions in which the pinning potential for trapped fluxons lacks inversion symmetry (ratchet potential). This system can be modelised by a set of non-linear pendula with alternating lenghts and asymmetric harmonic couplings. We show, by molecular dynamics simulation, that fluxons behave as single particles in which the predictions for overdamped thermal ratchets can be easily verified. Directional motion (DM) of brownian particles has been a target of basic and applied research in the last five years. The initial motivation and interest in this field came from cell biology: The study of the mechanism of vesicles transport inside eukariotic cells, via motor proteins along microtubules [1, 2]. Later on new systems with the same underlying ideas for transportation were proposed. Those systems include: phase separation engines[3], drop motion